As Reid says your DDP credits are valid from checking in to midnight the day you check out.
For tickets the official line from Disney is they are 14 day tickets If you use them on the evening you arrive (say Saturday) then the expire Friday. Unofficially they should expire on the Saturday the day you check out, I proved this to be the case last August. Our 14 day tix worked 15 days and our 21 days worked 22 days.
I will be checking again next week. I will activate on Saturday and then call in guest services for an expiry date. If I don't manage to do it with our 21 day tix before we upgrade to AP's I will check with 14 day tix our relatives have.